/*
 * Copyright 2016 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.util.internal;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.util.List;

public final class ThrowableUtil {

  private ThrowableUtil() {
  }

  /**
   * Set the {@link StackTraceElement} for the given {@link Throwable}, using the {@link Class} and
   * method name.
   */
  public static <T extends Throwable> T unknownStackTrace(T cause, Class<?> clazz, String method) {
    cause.setStackTrace(
        new StackTraceElement[]{new StackTraceElement(clazz.getName(), method, null, -1)});
    return cause;
  }

  /**
   * Gets the stack trace from a Throwable as a String.
   *
   * @param cause the {@link Throwable} to be examined
   * @return the stack trace as generated by {@link Throwable#printStackTrace(java.io.PrintWriter)}
   * method.
   */
  public static String stackTraceToString(Throwable cause) {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    PrintStream pout = new PrintStream(out);
    cause.printStackTrace(pout);
    pout.flush();
    try {
      return new String(out.toByteArray());
    } finally {
      try {
        out.close();
      } catch (IOException ignore) {
        // ignore as should never happen
      }
    }
  }

  public static boolean haveSuppressed() {
    return PlatformDependent.javaVersion() >= 7;
  }

  @SuppressJava6Requirement(reason = "Throwable addSuppressed is only available for >= 7. Has check for < 7.")
  public static void addSuppressed(Throwable target, Throwable suppressed) {
    if (!haveSuppressed()) {
      return;
    }
    target.addSuppressed(suppressed);
  }

  public static void addSuppressedAndClear(Throwable target, List<Throwable> suppressed) {
    addSuppressed(target, suppressed);
    suppressed.clear();
  }

  public static void addSuppressed(Throwable target, List<Throwable> suppressed) {
    for (Throwable t : suppressed) {
      addSuppressed(target, t);
    }
  }
}
